Solenoid assemblies are typically found in a myriad of modern products, from the control of anti-lock braking systems and dual-clutch transmissions in automobiles, to pressurized water control in irrigation systems, to more general uses such as in doors, windows, many hydraulic controls, and the like.
Solenoid assemblies are often provided with an outer casing used to hold and protect the inner components. This outer case, or housing, normally provides protection along the length of the assembly and may be augmented with the use of an end cap to protect the base of the assembly as well. The inner components can include features such as a solenoid coil, leads, and all valve components among other components deemed necessary by the specific process the assembly is involved in. In the instance of a spool and sleeve valve, an inner valve sleeve may be incorporated to allow for proper alignment of the spool and various other valve components, as well as for providing the necessary flow channels for the solenoid and spool to selectively control. The solenoid housing, along with this inner valve sleeve and other components, make up the structural backbone of the solenoid assembly. These structural components of the assembly are usually welded together to form a single structure or may be simply nested or stacked one inside of another to keep the interior components stable and to achieve more reliably repeatable function from the solenoid assembly.
The traditional methods of assembly, however, present several disadvantages. Welding the aforementioned protective and structural components of the solenoid assembly together can produce structural weaknesses at the welding junctions, leading to potentially vastly shortened operational lifespans. Further, with components often being of a relatively small size, the welding itself may require a significant amount of skill and time to produce a quality finished product. Simple nesting of these components may be advantageous compared to welding due to the increased ease of assembly, but that advantage could be mitigated by a loss of long-term durability.
Further, whether the method of assembly is from welding or nesting, components are still likely to be machined and assembled individually. Such practice can be highly labor intensive and time consuming and the machines required to produce these components are often expensive, large, and require a great deal of skill to operate properly.
U.S. Patent Application No. 2002/0047304 A1 teaches a valve sleeve which can be formed as a one piece closed end tube [0013]. More specifically, '304 teaches a FIG. 1, relating to an assembly providing a valve sleeve 16, flux return casing 21and valve casing 11. While valve 16 and flux return casing 21 appear to be integrally connected, assembly of these part is still required, such as by welding or stacking, and are therefore subject to all the above mentioned disadvantages of both. Further, valve casing 11 is separated from both the valve sleeve 16 and flux return 21, creating a disadvantageous weak point at the base of the valve sleeve 16. Finally, valve sleeve 16 is provided with a cap 40, as demonstrated in FIG. 3. The two components are assembled through a traditional welding process, once again making the solenoid assembly subject to all the disadvantages associated with such assembly processes. “In the preferred embodiment, the cap 40 is secured to the sleeve 16 by a conventional welding process, such as, for example laser or friction welding.” [0029]
U.S. Pat. No. 7,665,713 B1 appears to show an integrated solenoid assembly in FIG. 7, which portrays features of a solenoid 20B comprising a main outer cylindrical shell or housing 46, central spool 48, and a pair of yokes 50 among other features. As is evident from FIG. 7, the structural components of solenoid 20B must be assembled, creating inherent weak points in the construction.
U.S. Pat. No. 5,301,920 discloses a FIG. 3, which shows a body 30 of a solenoid valve, further comprising a valve sleeve 31. However, the assembly of the apparatus is accomplished simply by stacking the individual components in the body 30, and is then held in claims through the use of guide portions in the body 30. “In this embodiment . . . sleeve 31 . . . (is) guided by the respective guide portions formed on the inner wall of the body 30 . . . Also, since . . . sleeve 31 (is) installed simply by stacking them in the body in this order, the construction is simplified and the assembling work is facilitated” (col. 6, lines 52-63). The prior invention, therefore, appears to actually teach away from an integrated sleeve and housing design in the interest of ease of assembly.
U.S. Pat. No. 5,603,483 discloses a valve sleeve as shown in FIG. 5 and a solenoid assembly embodiment in FIG. 4 featuring said valve sleeve. However, the various components of the housing and internal sleeve components are obviously assembled from individually machined pieces and therefore are subject to the inherent disadvantages mentioned above.
What is desired, therefore, is a method of making a solenoid housing and a valve sleeve that reduces the structural and fabrication complexity in the above prior art. Also desirable is to have a solenoid housing and valve sleeve that do not require the individual machining of components and the potentially complex assembly of those components. It is further desired to have a method that not only reduces the mechanical complexity, but produces a product with an improved lifespan and durability from the elimination of unnecessary weak points introduced through assembly processes such as welding, stacking, and the like. In addition, it is desired that while eliminating all the aforementioned disadvantages, there should be no sacrifice of manufacturing efficiency, no significant increase of cost, and no decrease in performance.